This invention concerns yttrium tantalate phosphor. Examples of such a phosphor are disclosed in U.S. Pat. Nos. 4,225,653, 4,387,141, 4,970,024 and 5,009,807. However the phosphors disclosed therein are activated phosphors. That is to say, the wavelength at which the phosphors emit is primarily determined by the activating ion. For example, niobium activated yttrium tantalate emits at about 410 nanometers.